ZnTe Nanowires with Oxygen Intermediate Band Grown by Bismuth-Catalyzed Physical Vapor Transport

Abstract

We investigated the growth of ZnTe nanowires by a physical vapor transport method catalyzed by Bi. Straight and single-crystalline nanowires were grown at relatively low substrate temperatures (410∼360 °C). Micro-PL measurements revealed an unexpected color-tuning effect from green to red as the laser excitation position was moved from the tip to the bottom of nanowire. The red photoluminescence band can be ascribed to the highly radiative intermediate band formed by nonintentional O-doping from residual O2/H2O vapor. As the growth of nanowires proceeds, O-containing species diffuse through the side walls of nanowires. In addition, with changing laser excitation intensity, a similar color-tuning effect due to the interplay between red and green photoluminescence bands was observed. The red band dominates photoluminescence at low excitation intensity due to the fast electron relaxation to intermediate band. ZnTe NWs with this intermediate band may be useful for high efficient solar cells and two-color phot...